Creating a jet impingement pattern for a thermal control system
In one embodiment, a head assembly to be adapted about a solid immersion lens includes a plurality of jets configured in a radial pattern that extends from a central portion to a substantial periphery of the head assembly. The jets may expel a liquid coolant stream to cool a semiconductor device with a radial impingement pattern so that the liquid coolant travels from a central portion of the semiconductor surface to a peripheral portion of the semiconductor surface. Other embodiments are described and claimed.
During the design and manufacture of semiconductor devices, oftentimes debug and validation processes occur in which a prototype semiconductor device is subjected to various electrical and other testing to ensure desired performance. One such testing mode that is used in advanced semiconductor devices includes optical testing implemented with a solid immersion lens (SIL), which receives optical energy emitted from the semiconductor device during injection of high speed electrical signals into the semiconductor device.
A solid immersion lens (SIL) requires direct contact with the silicon die to allow probing using a prober tool to debug and validate a semiconductor device. Providing an adequate thermal management solution to maintain maximum die temperatures between −10° Celsius (C) and 110° C. at core peak power densities of greater than 500 watts per square centimeter (W/cm2) is a very challenging task for the following reasons. First, thermal heat spreading from circuitry such as processor cores is inhibited by removing an internal heat sink and thinning the die from 700 microns (um) to between 10 and 100 um. Second, the SIL lens form factor occupies 90% of the volume that could be used for heat removal via conduction, convection, or boiling. The SIL lens must move around the die, preventing any use of a heat sink attached on a backside of the die. Third, the thermal environment is expected to get worse as power densities are anticipated to exceed 560 W/cm2 of total die power.
Cooling solutions to date have used a spray coolant flow pattern that begins at the outer edges of the die and converges to a stagnant pool of liquid across the middle of the die, called the stagnation zone. This stagnation zone surrounding the lens itself exhibits poor convective heat transfer coefficients and results in high die temperatures and large die thermal gradients near the lens.
In various embodiments, a thermal management system for integrated circuit (IC) testing can be realized to enable cooler die temperatures while performing high speed testing. In various embodiments, a cooling system may be provided for use in connection with SIL probing. The thermal management system may include a plurality of jets in an assembly adapted about the SIL to enable cooling of the die undergoing testing.
According to different embodiments, different jet patterns may be provided in such an assembly to enable transfer of a liquid coolant as jet streams that impact the die and travel across a portion of the die surface to enable greater cooling performance.
Referring now to
The inward-out jet impingement cooling solution uses water to cool the die during SIL probing at fluid temperatures between 0° C.-110° C. via single phase convection heat transfer. At temperatures below 0° C., inhibitors such as methanol, propylene glycol, or ethanol can be mixed with water to depress its freezing point. A liquid pump delivers the fluid to a reservoir and then to a header that either surrounds the lens in the form of a sleeve or that is incorporated directly into the SIL lens cap.
The flow on the surface of the die that results is a spider-web pattern, as shown in
While shown with this particular implementation in the embodiment of
For example, the specific inward radial jet impingement pattern 200 has an interstitial pattern 210 towards the center of the lens with a velocity component directed at the lens center 225, enabled by corresponding groups of spirally aligned jets 205, which may be adapted between corresponding linear tracks formed of a plurality of linear radial jets 220, which may cause an aligned jet pattern moving toward the periphery. The interstitial pattern 210 thus produces a swirling or cyclone effect of the fluid near the lens tip. The fluid exits each of the jets in the jet header, impacts the die, moves toward the lens cap in a swirling fashion, moves downward with gravity along the lens cap or other housing and horizontally along the channels to the drain.
Referring now to
Referring now to
While shown as being formed in a generally outwardly manner in the embodiment of
Still referring to
The performance of an embodiment of the present invention has been demonstrated through examples and can be quantified by a convective heat transfer coefficient, which is defined as:
where hconv is the convective heat transfer coefficient, q″ is the heat flux from the die surface, Tjmax is a maximum junction temperature and Tfluid is the fluid temperature. By using Equation 1, the minimum heat transfer coefficient in the flow pattern shown in
Embodiments thus enable peak power densities to be cooled with a full probing range of −10° C. to 110° C. In addition, the embodiments provide for a much better die temperature uniformity around the lens over a spray cooling solution.
While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.
Claims
1. An apparatus comprising:
- a chamber having a top side to receive a semiconductor device under test (DUT);
- a solid immersion lens (SIL) adapted within the chamber to receive optical energy from the semiconductor DUT during a test operation; and
- a head assembly adapted about the SIL, the head assembly including a first plurality of jets configured in a radial pattern, the radial pattern extending from a central portion to a substantial periphery of the head assembly, each of the first plurality of jets to expel a non-atomized liquid coolant stream to cool the semiconductor DUT, wherein the non-atomized liquid coolant stream is to contact a surface of the semiconductor DUT with a radial impingement pattern so that the non-atomized liquid coolant travels starting from a central portion of the semiconductor DUT surface to a peripheral portion of the semiconductor DUT surface.
2. The apparatus of claim 1, wherein the first plurality Of jets are adapted outwardly from the central portion of the head assembly at an angle of less than approximately 20° with respect to a first axis normal to the semiconductor DUT surface.
3. The apparatus of claim 1, wherein the non-atomized liquid coolant is to provide single phase conduction heat transfer from the semiconductor DUT to the non-atomized liquid coolant.
4. The apparatus of claim 1, wherein the radial impingement pattern corresponds to a substantially spider web pattern.
5. The apparatus of claim 4, wherein the head assembly is a lens cap of the SIL.
6. The apparatus of claim 1, wherein the apparatus is to enable the semiconductor DUT to be probed at a peak power density across a probe range of between approximately −10° Celsius (C) and approximately 110°.
7. The apparatus of claim 2, further comprising a second plurality of jets configured in a substantially spiral pattern, at least some of the second plurality of jets configured between linear tracks formed of the first plurality of jets.
8. The apparatus of claim 7, wherein the second plurality of jets is to cause a second impingement pattern to move the non-atomized liquid coolant to the central portion of the semiconductor DUT and having a tangential velocity component to move the non-atomized liquid coolant away from a tip of the SIL.
9. A system comprising:
- a solid immersion lens (SIL) located within a chamber and adjacent to a semiconductor device under test (DUT) to receive optical energy from the semiconductor DUT during a test operation;
- a head assembly adapted about the SIL, the head assembly including a first plurality of jets configured in a radial pattern, the radial pattern extending from a central portion to a substantial periphery of the head assembly, each of the first plurality of jets to expel a liquid coolant stream to cool the semiconductor DUT, wherein the liquid coolant stream is to contact a surface of the semiconductor DUT with a radial impingement pattern so that the liquid coolant travels from a central portion of the semiconductor DUT surface to a peripheral portion of the semiconductor DUT surface;
- an array adapted to a periphery of the head assembly, wherein the array includes a second plurality of jets to expel the liquid coolant stream in a uni-directional pattern such that a uni-directional impingement pattern occurs so that the liquid coolant travels from a proximal side of the semiconductor DUT surface with respect to the array to a distal side of the semiconductor DUT surface with respect to the array;
- a collector adapted below the head assembly, the collector to collect heated liquid coolant traveling off of the semiconductor DUT surface;
- a chiller coupled to the collector to receive the heated liquid coolant and to cool the heated liquid coolant; and
- a reservoir coupled to the chiller to store the liquid coolant and to provide the liquid coolant to the head assembly.
10. The system of claim 9, wherein the first plurality of jets are adapted outwardly from the central portion of the head assembly at an angle of less than approximately 30° with respect to a first axis normal to the semiconductor DUT surface.
11. The system of claim 9, wherein the radial impingement pattern corresponds to a substantially spider web pattern.
12. The system of claim 10, further comprising a third plurality of jets configured in a substantially spiral pattern, at least some of the third plurality of jets configured between linear tracks formed of the first plurality of jets.
13. The system of claim 12, wherein the third plurality of jets is to cause a second impingement pattern to move the liquid coolant to a central portion of the semiconductor DUT and having a tangential velocity component to move the liquid coolant away from a tip of the SIL.
Type: Application
Filed: Oct 15, 2007
Publication Date: Apr 16, 2009
Patent Grant number: 7639030
Inventor: Robert Wadell (Sacremento, CA)
Application Number: 11/974,613
International Classification: G01D 21/00 (20060101);